In testing a model that predicts the configuration of alcohols produced in the enantioselective hydrolyses of racemic acetates by Rhizopus nigricans, we found that the relative sizes of substituents deduced from these hydrolyses are in agreement with those based on other asymmetric syntheses, with the exception of the t-butyl group. The "effective sizes" of cis-substituents on the stereochemical course of the hydrolyses of cyclic acetates have been determined to be similar to those of trans-substituents. The compounds prepared by microbially mediated reductions and hydrolyses have been used to test the suggestion that the elution order of enantiomers on a chiral HPLC column can be used to assign their absolute stereochemistry. The results to date show that retention volumes and configurations generally correlate well. There are, however, a few exceptions which are the subject of further study. Photochemical isomerization of 2-phenylindene oxide has been shown to yield 3-phenylisochromene. No products from phenyl migration were detected. Photochemically induced isomerization of 1,2-dihydronaphthalene oxide yielded beta-tetralone.